Heavy rare earth elements (HREEs) are more important than light rare earth elements (LREEs) since the supply risk and application in clean energy. In this paper, we first reported the synergistic extraction based on 2-ethyl(hexyl) phosphate mono-2-ethylhexyl ester (EHEHP)-type and bis-(2,4,4-trimethylpentyl) phosphate (BTMPP)-type acid base coupling bifunctional ionic liquids (ABC-BILs) for HREEs separation. Extractabilities of the novel systems were better than those of mixed 2-ethyl(hexyl) phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) and bis(2,4,4-trimethylpentyl) phosphinic acid (HBTMPP). Also, stripping property of the ABC-BIL based synergistic extraction system for HREE was better than that of mixed HEH[EHP] and HBTMPP. Advantages of the novel synergistic system based on ABC-BILs have revealed potential application values for HREEs separation industry.